The Union Association was a Class D level Minor league baseball circuit that operated from 1911 through 1914, with franchises based in Idaho, Montana and Utah.
Beginning play in 1914, the Union Association was classified as a Class D league, based in the Rocky Mountains of the Western United States.
The 1911 charter members were the Great Falls Electrics, Salt Lake City Skyscrapers, Butte Miners, Boise Irrigators, Helena Senators and Missoula.
The Salt Lake City, Helena and Ogden franchises played for the entire duration of the Union Association.
Despite the rest of the league disbanding, Salt Lake City and Ogden played 16 games against each other to complete their seasons.